Multi extrude a vertex in the coordinate direction
I've uploaded on GitHub a script that allows you to extrude selected vertices in all directions.

https://github.com/parameciostudio/extrude-vertices-all-directions

You can set the amount and choose whether select created vertices or not.

How to install

Open up extrudeVerticesAllDirections.py in the Text Editor and press Alt+P

How to use


Select a mesh object and toggle into Edit Mode (Tab)
In the MISC tab of the Tool Shelf (T) you'll find a new Extrude in all directions panel
Set the extrusion amount and whether select new vertices or not (if not, original vertices will still selected)